It's been a long two weeks since Clary, Jace and Simon visited the Seelie Court and had their love triangle well and truly put to the test, but Shadowhunters is back this week, and it definitely packs a punch! Following on from Episode 14, this week's #Shadowunters showed us a multitude of things, tying up some of the previous episode's loose ends. Not only did we have a really good look at who Sebastian is keeping locked in his apartment, we also saw the repercussions of Clary's actions at the Seelie Court, as Simon and Clary's relationship took a turn for the worse.

With a visit to The Institute from new character (and fan favourite amongst book readers) Aline Penhallow, Episode 15 of Shadowhunters made important strides in setting up the tone for the rest of the season. Keep reading to see the top 3 things we learned this week!

1. Simon's Made His First Vampire Kill — But It's Not Who You Think

Many of the promo's released before this week's episode showcased Simon's downfall as he reeled from the effects of Clace's steamy kiss in Episode 14. Naturally, Simon had a lot on his mind, not least because a mere week before that, the entirety of New York's Vampire Clan discovered that he is a Daylighter.

At a bar shortly after the Seelie Court meeting, Simon runs into fellow Vampire, Quinn, who offers him a shot of "something stronger" aka Plasma. The shot takes instant effect, and with most of his troubles and woes temporarily put aside, the somewhat gullible Simon then follows Quinn to what is known as a Bleeder Den. It's essentially Fangtasia from True Blood, toned down for Freeform's largely teenage audience, and is filled with Mundanes looking for a Yin-Fen (Vampire venom) high.

It's at this Bleeder Den that Simon is introduced to Heidi, a Mundane basically looking for a Yin-Fen high and a good time. Unfortunately, Heidi is found dead early the next morning, and with Simon's watch found on her and blood soaked into his shirt, he's the NYPD's number one suspect.

After a little investigating — most of which consisted of Simon blaming himself for Heidi's death — Simon discovers that he didn't kill Heidi after all. When Luke's cop partner let's slip that the wounds which killed Heidi were on her feet, Simon realises it's Quinn who killed her, and thus he heads back to the Bleeder Den to confront him, eventually killing Quinn after the two brawl with makeshift stakes.

Shortly after this, Clary attempts to comfort Simon. After all that's happened, Simon admits that he needs some space, athough he'll always be friends with Clary. The two then agree to take some time apart.

2. Sebastian Struggles To Maintain His Identity — Will He Reveal Himself To Valentine?

Since his arrival, Sebastian has been a seemingly helpful ally to the Shadowhunters, a good friend to Izzy, and a slightly creepy fellow to us viewers at home. In Episode 14, we saw Valentine almost recognise him after Luke had attempted to kill him and Sebastian intervened. Of course it was also revealed at the end of that episode, that it was Sebastian who had made the call to Luke via the burner phone, and gave him full access and clearance to kill Valentine.

This week, Sebastian found the identity he's fought so hard to keep began to falter as his cousin, Aline Penhallow, came to visit. In the books, the two are quite close, but Aline seemed somewhat taken aback by Sebastian as he didn't quite seem himself. Shortly after this encounter, in which Sebastian smoothly manages to hide his true agenda, we have our first real look at who Sebastian is keeping locked up in his apartment.

'Shadowhunters' [Credit: Freeform, Netflix]

Bizarrely, Sebastian appears to be threatening himself as he crouches opposite a man who is his exact twin. When he tells his "twin" to reveal everything he knows about Aline Penhallow, it becomes obvious that the man Sebastian has been keeping locked up, is in fact the real Sebastian Verlac. Which of course begs the question, who the hell is the guy walking around with Sebastian Verlac's face? The guy who's been in and out of The Institute the past 3 weeks, and who helped Izzy overcome her Yin-Fen addiction?

Well, he's Jonathan Morgernstern of course, Valentine's real, actual, blood-related son. Jonathan ends up kidnapping Valentine at the end of the episode — after killing the real Sebastian just as he was about to reveal himself to Aline and Izzy. Jonathan then reveals himself to be Valentine as his son, showing a form that is burned and charred and completely unlike the friendly face of Sebastian we've become used to.

Valentine is currently the only person who truly knows who Sebastian (Jonathan) is, and with the real Sebastian dead, there's no one to question his identity, or threaten the truth coming to light. We also know that Sebastian (Jonathan) was the figure who walked off at the end of Season 2A with the Soul Sword — one of The Mortal Instruments — and that Valentine (who is currently Sebastian's (Jonathan's) prisoner) is the only person who knows the location of The Mortal Cup.

3. Magnus Relives His Painful Past — But Is He Pushing Alec Away In The Process?

We haven't seen a whole lot of Malec since Alec's declaration of love in Season 2A, but we were blessed with a little more depth in the relationship of the show's fan-favourite couple this week. Waking up in bed alone for the third morning in a row, Alec realises there's something wrong with Magnus. Initially, Alec decides to give Magnus some space, but after a talk with little sister Izzy, Alec changes his attitude.

'Shadowhunters' [Credit: Freeform, Netflix]

Alec demands that Magnus tell him what's wrong, and insists that he won't leave until Magnus shares what's troubling him. It is here that Magnus reveals he's still reeling from the effects of the body-swap with Valentine, and the torture he suffered at the hands of the 'Agony' Rune. Magnus confides in Alec, telling him that the effects of the Rune are making him relieve his worst memory — the one of his mother's suicide.

In a flashback, we see a younger, altogether more adorable Magnus discover his mother's dead body with the knife still stuck in the fresh wound. She'd bled out all over the bed, and when Magnus's stepfather finds little Magnus beside his mother's dead body, his stepfather blames him, calling him an "abomination" in the process.

With his emotions high, young Magnus's cat eyes glow as he uses the full extent of his power to burn his stepfather alive. Present day Magnus, embarrassed and ashamed of his past, insists that he never wanted Alec to see this "terribly, ugly" side of him. Despite Magnus's shame, Alec stands by his side, both literally and metaphorically, and comforts him before telling Magnus not to push him away when things get crazy. (In the same way that Magnus told Alec, after he killed Jocelyn whilst possessed by a greater demon).

Next week's Episode is set to raise the stakes, as Clary appear to be back creating new Runes, Angels have clearly returned to earth, and both Sebastian and Jace seem to be exhibiting new powers. To make sure you never miss a moment, tune into Shadowhunters Mondays at 8/7c on Freeform, and Tuesdays on Netflix for us international fans!

Which character do you think will be the first to find out who Sebastian really is? Izzy, Clary or Jace? Let me know in the comments!